Since this is rather recent question and not marked as solved, I'm trying here to get answer to my similar problem. I am using same options menu defined in action_bar.xml, for several activities. It doesn't show on every activity. When I put android:showAsAction it works on this layout file:
When I put myapp:showAsAction it shows on another activity with different layout file (and don't show on first one):
All activities are made from templates but I don't recall if it was the same template. Thanks for any hint, I guess it's about some Activity attribute.